What is spreidsel?
Spreidsel is thin, quarter-sawn oak laid flat between the common joists, directly under the floorboards. The term is Dutch and has no exact English equivalent; you could describe it as a thin oak ceiling boarding between the joists. Seen from below, it hides the underside of the floorboards and stops dust and sand from falling through the gaps between the boards. You mainly find it in historic Dutch buildings with a floor of summer beams and common joists.
Characteristics
- Thickness. Spreidsel is only a few millimetres thick, roughly 3 to 8 mm.
- Attractive figure. Because it is quarter-sawn, the wood often shows ray fleck (medullary rays) and parallel lines of the growth rings.
- Several pieces per bay. The boards are often shorter than the bay between two joists, so each bay needs several pieces.
- Cover strips. The joints between the boards were covered with narrow strips, sometimes purely for appearance.
- End boards. Vertical boards between summer beam, floorboards and spreidsel closed off each bay at the ends.
Why spreidsel?
- Gaps between the floorboards are no longer visible from below.
- No dust falls from the ceiling.
- Noise between storeys is slightly reduced.
A simpler alternative was to seal the board joints with felt or paper.
Application
- Record before dismantling. Number the boards and strips and take photos, so everything goes back in the same place.
- Work carefully from above. The thin wood splits easily. Lift floorboards slowly and never put weight on the spreidsel.
- Repair like with like. Replace damaged pieces with quarter-sawn oak of the same thickness, otherwise the difference stands out.
- Check the timbers. An opened floor is a good moment to inspect joists and beams for rot and insect attack.
Common mistake: ripping out spreidsel during a renovation, or hiding it above a suspended ceiling, without realising its heritage value. For a listed building, consult the local authority first.
Related terms
- Common joist
- Summer beam
- Quarter-sawn timber
- Wooden floors
- Beam
- Holes in wooden beams
Want to know more about building terms? Visit our knowledge base at fredsdiyplans.com.